"It's a magpie nest," says designer Alice Temperley of her loft, the top half of a converted nineteenth-century barn, which sits above her shop in London's Notting Hill. At the moment it's partially roofless—she's expanding her territory to the flat next door. "It's pissing rain at the moment," says a lithe, rosy-cheeked Temperley as she measures a giant old-fashioned-looking gold and black onyx cocktail ring—the first piece in the Temperley jewelry line, which her sister, Mary, designed for fall. "Five centimeters long!" she says triumphantly. "Every model we sent down the runway had one of these on."

The designer has long cultivated a love of huge, eye-catching accessories. "I like jewelry to be bold. I don't like anything little or fiddly," she says. In addition to her stock of flamboyant mirrored headdresses (which make for popular party hats at her late-night dinners), found everywhere from flea market tables at the UK's Glastonbury Festival to the farthest reaches of Bali, Temperley has an extensive trove of Victorian baubles, bracelets, and necklaces— some of which inspired pieces in her fall collection. "I found this 1920s beetle-wing necklace at a vintage fair in London; it reminded me of earrings I had as a child," says Temperley, who translated the piece's iridescence into a gold-foil jersey fabric—custom-made at a mill in Como, Italy— which became a slinky, mermaid- shape evening gown.